BILLINGS, Mont. - Prosecutors say they no longer will pursue the death penalty against a Colorado man suspected of killing a teacher in eastern Montana's oil patch.
The move by Richland County Attorney Mike Weber comes after psychiatrists determined 25-year-old Michael Keith Spell is mentally disabled.
Prosecutors say Spell and Lester Van Waters, Jr., abducted Sherry Arnold in January 2012 while the teacher was out for a morning jog. They are accused of killing her and burying her body in a North Dakota field.
Weber cited a 2002 U.S. Supreme Court ruling that said executing mentally disabled criminals constitutes cruel and unusual punishment.
A state judge on Friday rejected attempts by Spell's attorneys to have him declared incompetent. That would have let him avoid trial.
Spell now faces a maximum of life in prison if convicted on charges of attempted kidnapping and deliberate homicide.
Waters accepted a plea deal in which he plead guilty to deliberate homicide by accountability. In exchange, prosecutors dropped an attempted kidnapping charge and will recommend a sentence of 100 years in prison with 20 years suspended.
Waters and Spell are from Parachute, Colo.